Current echocardiographic techniques for detection of ischemic heart disease are largely dependent upon the presence of regional abnormalities of wall motion. However, the presence of abnormal wall motion does not distinguish regions of ischemia from regions of infarction. Characterization of the tissue by direct ultrasound interrogation procedures represents a promising new technique. As an additional approach, injectable agents which enhance myocardial ultrasonic reflectivity will be investigated with two-dimensional echocardiographic imaging. Echo-enhancing agents including microbubbles, lipid-containing emulsions and micro-encapsulated peroxides will be investigated with regard to their relative echo-enhancing capabilities and toxicity in an animal model. Initially, materials will be injected directly into a coronary artery. After determination of acceptable enhancement/toxicity ratios, the site of injection will be removed progressively further away from the coronary circulation and states of altered coronary flow will be studied. Ultrasonic images will be obtained using a phased-array sector scanner and recorded on videotape for visual and optical analysis. Dose-response curves will be constructed. The ultimate goal of this proposal is the development of a perfusion indicator that can discriminate regions of normal from those of abnormal coronary perfusion utilizing commercially-available two-dimensional echocardiographic equipment.